Robert Titus

The Glaciers got There First

The Catskill Geologists; May 19, 2019

Robert and Johanna Titus

Have you been to the Walkway across the Hudson at Poughkeepsie? It’s a pedestrian bridge that, high up in the sky, crosses the river; We promise you, it’s quite the experience. But, opening next week, (2019) is something just as good and a lot closer. That’s the Hudson River Skywalk. The Skywalk also spans the Hudson, this time across the Rip Van Winkle Bridge. In so doing, it links two important historic sites: Frederic Church’s onetime home, Olana, and Cedar Grove, the Thomas Cole Historic Site. The new trail extends from Cedar Grove, across the bridge. and then it ascends the hill to Olana. Can there be a “theme’ to a walkway? If so, with this one it’s the Hudson River School of Art. Cole and Church were that “School’s” two leading lights.

We said that the Skywalk was just as good as the Walkway, but maybe we can write about something that makes it even better. If you get a chance and you head out over the Hudson, we would like you to look and see how steep the slopes are on either side. We are talking about the slope just beneath the western end of the bridge and the other slope just beneath Olana. That steepness is something that is not always easy to take notice of, but it is important. Shouldn’t there be a floodplain? Rivers are supposed to flow across broad, flat floodplains, aren’t they? So, why not here?

The Skywalk – Picture courtesy of Olana

We got to thinking about that and came up with an answer, a good geological answer. Halfway across the bridge we looked east and west and then north. In our mind’s eyes we saw a glacier. It was perhaps 14,000 years ago and, for the most recent time, an ice age glacier was advancing down the Hudson Valley. That glacier rubbed up against the slopes on both sides of the river. Glaciers can be very erosive and this one was no exception. It cut into Church Hill where Olana is perched. That would greatly improve the view that Frederic Church would eventually paint. It also cut into the western side of the river. All this erosion left no room for any kind of floodplain. Instead, it formed a rather boxy valley with a sizable river flowing down a surprisingly narrow pathway. You probably never noticed this, did you? Well, go out onto the Skyway and take a look.

The official opening is set for June 1^st (2019). People will congregate at Olana and at Cedar Grove. Each group will set out on a “parade” to the Skywalk Trail. If all goes well, they will all meet at the middle of the bridge. There will be a ribbon cutting at the park near the bridge’s toll plaza at noon. We don’t think there will be a golden spike, but it should be a fun event.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Joints along Rte. 145

The Catskill Geologists; The Mountain Eagle, May 16, 2019

Robert and Johanna Titus

Science may seem cut and dried to many. We scientists just know everything, don’t we? We look at things and figure them right away. Don’t we? Well – no, and no again. Sometimes we see things that we just can’t figure out. The two of us have been having that sort of a problem lately and it all began along Rte. 145, That’s at the top of the hills you see as you approach Middleburgh from the south. On the right side of the highway is an impressive outcropping of typical Catskill sandstone. Take a look at our photo.

That outcrop makes up a very fine wall of rock. It actually seems too fine. The rock exposes several nearly perfect, smooth and upright surfaces – too smooth and too upright.  What is going on here? Rocks are supposed to break up into jagged rough blocks, aren’t they? It looks like we have some explaining to do.

These surfaces are fractures in the rock that are called geological joints. There is a good bit of scientific theory behind this. Joints record chapters in the tectonic history of a region. They began to form when the rocks, long ago, came to be compressed during a tectonic event. It may be hard to imagine that rocks can be squeezed, but they can. That requires immense pressures, but such pressures do occur within the Earth’s crust – deep within the crust.

Now the funny thing about all this is that rocks do not fracture when they are being compressed; they have enough “give” to absorb that stress. But compression does not last forever; it eventually does end. Rocks then expand and that is when the fracturing begins. There is a sort of relaxation which occurs as the pressure eases. At that moment we find that rocks are brittle, and it is exactly then that they crack to form joints. So, what triggered all this? We need more scientific theory.

Cycles of compression and relaxation, strong enough to deform and fracture rocks, can only be associated with the truly great tectonic events. These are not just run of the mill earthquakes; these are the towering mountain building events. And the one which triggered our Rte. 145 joints was one of the biggest mountain building events ever. That was the collision of Europe with North America, about 400 million years ago; it made the northern Appalachians. Episodes of compression and relaxation, associated with massive uplift of the crust, is what created these joints.

All this is good sound scientific theory, so what’s the problem? Take another good look at our photo. Do you see how it appears that large masses of jointed rock came to be yanked out of the ground and carried off toward we, the photographers. How on earth did that ever happen? Well, that’s our problem. We can tell you how we would like it to have happened. We stand there and imagine a glacier rising up the valley. The west moving ice passes by and forms a bond with the bedrock. Ice does that; stick your tongue to the bottom of an ice tray and you will find out for yourself. Well, as the ice continued up the valley, it did that yanking; blocks of rock were plucked out of the ground and dragged off toward Middleburgh.

At least we would like that to have happened; it would be such a nice vision of ice age history. But just can’t convince ourselves that it happened that way; road building seems very likely to have helped out, and that takes the Ice Age out of the story. So, where does that leave us? Well – with an unsolved mystery. We’ll figure it out someday -and get back to you about it.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Brachiopods

The Catskill Geologists; May 25, 2018

Robert and Johanna Titus

If you do a lot of fossil hunting in the Catskills then you probably already know much about what we will be writing this week. But, even if you do, you may well find our column worth reading. It’s about a group of invertebrate shellfish that lived right here. And we mean right here. Look around you. Where you are now was once the bottom of an ocean called the Catskill Sea. That sea takes us back roughly 400 million years ago to the Devonian time period. Now take a look at our photo; it’s a piece of sandstone. Its flat surface is a petrified bit of that sea floor. And, just as it was hundreds of millions of years ago, it is littered with shellfish, now fossils. They are brachiopods. We see them on this rock – right where they lived and right where they died.

These animals, in life, lived within two shells so you might be tempted to call them clams. The similarity to clams is accidental. Brachiopods are a very different group of animals. Their internal, soft anatomy is entirely different from that of clams. Brachiopods are not even mollusks. We have blown up the image of one of these brachiopods in our second photo. Notice that there is a plane of symmetry running down the center of the shell. With clams there are also planes of symmetry but they are found in between the shells, not down their centers. Using symmetry you can always quickly tell apart clams from brachiopods. All this is important because these two groups are the most common fossils found in the deposits of the Catskill Sea. You need to know the difference. With experience that will soon become second nature.

All but one of these fossils belongs to a form of brachiopods called Mucrospirifer. Mucrospirifer shells are categorized by their heavy ridges and those two – tapering left and right – extensions, sometimes informally called “wings.” Mucrospirifer is a very common brachiopod in our region’s marine sedimentary rocks. It enjoyed great success during the Devonian. There is a second species of brachiopod in the upper right corner of our first photo. It too has a plane of symmetry running down the center of its shell.

There are more things that need to be explained here. First, notice how many Mucrospirifers are seen on this bit of that ancient sea floor. And also notice that they are all just about the same size. We are guessing that this represents something that is common among marine invertebrate animals. Such creatures commonly begin life as single fertilized cells, zygotes that were cast out by their mothers. Alternatively, they may have been early and primitive larva. But in the end it was all the same; these very young invertebrates drifted with seafloor currents until they detected a suitable ecology and, then and there, they settled to the bottom and began their lives. A group of invertebrates of this sort, all the same size, is called a spatfall.

Another thing about these spatfalls is that they seem to us to be commonly found on very dark shales. Geologists generally assume that dark shales represent a quiet sea floor with a low oxygen content. If so, then much of the success of Mucrospirifer came from its ability to survive in a wide variety of environments, places that other animals found inhospitable.

But, in the end, what is important here is for you to learn about a common form of fossil, typical of our Catskills. Don’t your feel just a little smarter now that you have read our column?

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

A visit to an old cement mine

The Catskill Geologists; The Mountain Eagle May 9, 2019

Robert and Johanna Titus

One of the most sizable among today’s Catskills regional industries is the manufacturing of cement. Its operations lie mostly at Coeymans. It is thriving today but dates back to a distant past. The history of cement in the Hudson Valley began with our country’s entry into the industrial revolution. One of the great projects that heralded our industrial revolution was the building of the Erie Canal. Canals would help make America grow into a great economic powerhouse. But the building of canal systems required a lot of cement; where would it all come from?

Enter an important man, Canvass White. He patented a method for making durable, waterproof hydraulic cement, also known as “natural cement.” That’s a type of cement that, when mixed with water and allowed to set, becomes impermeable to water. It was made from two types of sedimentary rocks: limestone and its close cousin dolostone. When these rock types also have significant amounts of clay in them, then they can be manufactured into natural cement.

In 1825 large quantities of such rock were discovered in and around Rosendale. Canvass White went into the business. He was not alone; by the 1840’s there were a dozen or more cement operations in the Rosendale area. And, for the rest of the 19^th century, this industry would only expand; it became big business.

Today, the old Rosendale cement industry is memorialized and partially preserved at the Snyder Estate Natural Cement Historic District which covers about 275 acres. At the heart of this is the Century House Historical Society. They possess 18 acres of land which displays some of the old Rosendale facilities. A visit can be a bit of an underground adventure that we highly recommend.

Coming this Sunday, May 12^th, 2019 you can be taken for a tour of the Widow Jane Mine by society member Steve Schimmrich, professor of geology at Ulster County Community College. Steve knows his way around the site. When we joined him there, years ago, he took us to a sizable cliff, penetrated by mine entrances. We entered and found ourselves in what is called a “pillar and room” mine. Way back in the 19^th century, miners had excavated shafts into the mountain and then they expanded them until only the pillars were left behind. That allowed the removal of as much cement-producing rock as possible, leaving the pillars to prevent cave-ins. Back then, this was pretty impressive engineering.

Steve showed us the stratigraphy of the site. The cement producing rock is called the Rondout Formation and it is composed of three horizons of rock: the lower and older Rosendale Dolostone, the middle Glasco Limestone, and the upper and youngest Whiteport Dolostone. The Glasco Limestone was of no economic value, but it was fascinating to see. The Glasco accumulated at the bottom of a very shallow tropical sea and it was richly fossiliferous. Steve pointed out fossil corals that were very common in it. We were traveling abmost 420 million years into the past and looking at Rosendale when it was a shallow tropical sea, dotted with small coral reefs. Steve showed us an abundance of fossil shellfish too. We were thus able to see this ocean and its inhabitants. We saw a wave-swept and agitated sea floor, with an abundance of marine algae and colorful shellfish; it was a wonderful experience.

But it was the other two units of rock that had made all the cement. We looked up at another cliff and saw two horizons penetrated with rectangular mine openings. The lower one was the Rosendale and the upper level was the Whiteport.

Our tour continued, back outdoors, with Steve showing us the remains of the conveyer belt that once carried the dolostone out of the mine to where it was processed. That processing continued in kilns that are still present; there the rock was heated and eventually would be turned into cement.

All in all, the Schneider Estate does a very good job of preserving what it must have been like here when the last cement miner closed up shop and walked away. Time has decayed the site a bit, but it has not destroyed it. The industry began a rapid decline in the early 20^th century and the last production ended in 1970. Today all that is left is a well-preserved historic site; our thanks go to the Society for all their hard work.

Contact the authors at randjtitus@prodigy.net.

A fossil soil?

The Catskill Geologists; The Mountain Eagle, May 11, 2018

Robert and Johanna Titus

The intersection of Rtes. 23 and 32 is one of those locations that we just happen to pass all the time. We typically drive west on 23 and then turn right onto 32. But there is an outcrop on 23, just east of that crossroads. The strata there record the deposits of the outer edge of the old Catskill Delta. We are transported through time back about 385 million years, and find ourselves surrounded by a low, almost flat landscape, covered with a scrubby foliage of very primitive plants. Off, a short distance to the west, is the shore of something called the Catskill Sea. We can’t see those waters but we know they are there. We can smell the saltwater.

We stand on the shore of a sizable river which has flowed across the delta and is headed toward that sea. Its currents flow by us, right to left. The channel bottom is blanketed in soft light-colored sand. All around us is that foliage; it consists of relatively short tree-like plants; we would have to call them shrubs. They reach up to chest level. They are very exotic looking plants; none of them are alive today. To our eyes, they seem very primitive; we can’t guess why at first, but soon we notice that they do not have proper looking leaves, nor any flowers. Their bark is covered with a closely spaced ornamentation of diamond shaped scars. Nothing like them can be seen in the Catskills today.

We look down and see that the soil, beneath us, has the shade of a dull brick red. It is warm on this ancient day in this distant past, and that red soil tells us that this is the norm for these times. Not only have we traveled into the distant past but the climate here is tropical. The soil is a tropical one.

And, POOF, our journey into the past is over and we have traveled, in an instant, back to the present. We are again standing along the side of Rte. 23 – and we haven’t moved an inch. We look at that outcropping once again and see, for the first time, just exactly what is in front of us. There is a horizon of red strata. It is cut by vertical structures.

We are looking at a fossil soil. Above it, lies the gray sandstone strata of an old river channel, those other gray sandstones, below, are from another such river channel. But, it is that reddish horizon that captivates us. They document something that we are familiar with. Those vertical structures are shrinkage cracks. They form within soils that are subjects to alternately wet and dry seasonality. During wet seasons of the year, they soak up water and expand. But, during dry seasons, they desiccate and shrink. That’s when the cracks form.

Today, such soils are called vertisols, named after their vertical cracks. Now, we look at this soil profile again, and realize that we have been there. Just a short time ago we had traveled back in time and stood on the shore of one of those two rivers. And we had stood upon that very soil. We reach out and touch the top of that red soil horizon. And then we lean forward and look closely; we are searching for our own footprints. But we can’t find them; time travelers do not leave footprints in the past.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

A very old floodplain; a very new preserve

The Catskill Geologists; The Mountain Eagle, May 3, 2019

Robert and Johanna Titus

We have a new preserve in our region. It is called the Mawignack Preserve and it is located at Jefferson Heights, just west of downtown Catskill. It was officially opened last May (2018), and although we had been meaning to visit it, we had been too busy writing Mountain Eagle columns. When we finally got there a few weeks ago, we set about looking for something new to write about. It didn’t take long.

Actually, when we got to its parking lot and looked at a kiosk’s map of the Preserve, we became pessimistic. The Preserve appeared to be just a routine nature trail circling around a sizable meadow, nice but not promising much geology. We set out anyway. The trail soon took us to a right fork, and we went off in that direction. Soon, we looked to our left and saw a very recognizable feature. Take a look at our photo. Behind those trees you should see what looks like a curving river channel. It seems to meander left and then to the right. But it’s not a meandering river; the channel is empty.

This is, and at the same time, it isn’t a stream meander, what we were looking at is actually called a meander scar. It speaks to us of a river that, long ago, passed by right here, flowing through this now empty channel. We wrote about meanders and meandering stream last week. We found that rivers wind their ways across floodplains. What we didn’t mention is that these meanders don’t last forever. It is typical and normal for rivers to jump their channels and relocate themselves, often during terrible episodes of flooding. Something like that is what happened here, leaving an abandoned meander channel that has been slowly filling up with peat and windblown sediment for centuries – or perhaps millennia.

The Mawignack Preserve lies right next to today’s Catskill Creek and we are guessing that our meander scar represents a very old and very short stretch of that creek as it was in the distant ice age past. But we had another surprise coming. We followed the trail toward Catskill Creek. We now knew that we were walking across the stream meander’s old floodplain. But, when we got to the modern Catskill Creek, we found it to lie about 10 or 12 feet lower than the old floodplain.

How could that be? Geologists may have the answer to that question. They know that, as the glaciers melted at the end of the Ice Age, a lot of weight was melted away too. All that weight flowed as water into the sea. With all that weight gone, the crust actually rose. Our meander’s floodplain rose those 10 to 12 feet above the modern creek.

A story was emerging, and the Mawignack Preserve was getting more and more interesting. We had been transported, as time travelers, back to the very latest chapter of the Ice Age. Before us, an older and more powerful Catskill Creek was flowing by. The region’s glaciers were still melting. We couldn’t feel it, but the ground beneath us was rising. As it rose those 10 to 12 feet, Catskill Creek eroded into the rising ground to form its modern channel. The creek then drained off of the old floodplain and left the meander we had discovered high and dry.

That plain and simple walk on a nature trail had led to our discovery of an intriguing bit of ice age history.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Thomas Cole at Catskill Creek

The Catskill Geologists; The Mountain Eagle; April 12, 2019

Robert and Johanna Titus

We have been longtime members of Cedar Grove, the Thomas Cole Historical Site. They preserve the home of Thomas Cole, the man who is widely regarded as being the founder of the Hudson River School of Art, America’s first widely recognized school of art. Cedar Grove has also become a center for the scholarly and academic study of this art. Every summer Cedar Grove sponsors an exhibit of paintings done by artists of that “School.” This year’s exhibit (2019) will display a series of paintings done by Cole along Catskill Creek, just west of his home. Cole would pack up his sketch pad and pencils and make the short hike to what is today called Snake Road in Jefferson Heights, just a bit west of the Village of Catskill. He would sketch the view there and turn that sketch into a painting. He did the view at different times of the day and different times of the year. Much of his art is influenced by something artists call “luminism.” That style of painting allows an artist to experiment with the lighting. Where is the sun placed? Where is the sunlight highlighted? Where are the shadows? How much contrast is there and how bright are the colors? You get the idea; luminism is landscape art which is largely about color and light. It requires real skill and Thomas Cole had that. This summer’s exhibit has been curated by Dr. Daniel Peck, professor emeritus at Vassar College. The exhibit is coordinated with the recent release of his new book on those paintings. We know Dr. Peck and did a little geological advising on his research, so we are thrilled to see all this.

Like just about anyone else, we admire Cole for his artistic skills but, naturally, as geologists, we see things that most others don’t. Let’s talk about that today. Take look at our picture. It is one of about a dozen that will be in the exhibit. It displays a view of Catskill Creek sometime in the middle of the day, during high summer. There is, of course, a rich dark green foliage. In the distance is the Wall of Manitou, the Catskill Front. Two women sit on the slope above the river, probably enjoying the view. There is little, if any, evidence of human commercial or industrial activities. This painting was done before a railroad line was built in this location. That would show up in later Cole paintings.

The geology is in the river itself. Catskill Creek rounds a large sinuous bend as it flows right to left, which is west to east. Geologist call this sort of thing a river meander. We have explored the area and we do not think that this is a recent landscape feature. We noticed that the river has cut about ten feet down into the “floodplain.” That’s called an incised stream. That means this river meander formed in ancient times. Then the landscape was uplifted, we think about ten feet, and the meandering stream eroded downward the same amount. It restored its old level. Hence the incised meander. There is more to the story; we will pursue this in a later column.

Well, today’s column has been a mixture of geology and landscape art, but you can see how closely they are related. It was a geological history that created the landscape that Thomas Cole painted so well.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

We have a theory.

The Catskills Geologists; The Mountain Eagle; Apr. 20, 2018

Robert and Johanna Titus

If you want to be a scientist, then you have to learn how to be very careful with your use of language; you have to learn how to express yourself in very precise terms and with very accurate use of words. The two of us cringe almost every time we hear the word “theory.” The vast majority of people who use the word, don’t know precisely what it means. We had better explain.

People say theory when what they mean to say is guess or hunch. And that is sort of okay in everyday vernacular language. But, in science, the word theory has a very specific meaning. A scientific theory has, indeed, its birth in a hunch, but that notion of a hunch might be better described as an educated guess. It takes a long period of investigation before a scientist is able to even hazard such a guess. The word we scientists prefer is hypothesis. A hypothesis is not a theory, it is an early effort to explain something scientific.

Well, why is it not a theory? The answer is that the rules of science require that the hypothesis must be tested. The tests are in the form of if/then statements. For example, if AIDS is the product of HIV viruses then all victims of that dreadful disease will possess HIV viruses. They do, and the HIV hypothesis has passed its first test. Scientists typically go on to test their hypotheses, over and over again, before elevating any of them to the lofty status of a scientific theory.

Theories are considered “lofty” because they don’t just describe nature, they provide scientists with explanations of nature. They provide us with true understandings of natural processes. Those explanations have been tested over and over again. That means that, in science, the word theory does not invoke any guesswork. It is considered proven as much as any human being can prove anything. Even so, it is normal for scientists to go on and test their theories. We are never really satisfied; we always go on and test.
Much of our writings here in the Catskill Geologists column is based on the glacial theory. That theory maintains that much of the landscape that we travel across, here in the Catskills, was the product of the sculpting effects of glaciers about 20,000 to 12,000 years ago. Every time we write a column about that we are testing the glacial theory. We have never falsified it. We feel that we understand the Catskills a lot more because of that theory.

But there is another theory that governs our writings. That is the theory of the rocks, which was developed by a Scottish scientist named James Hutton in the late 18^th century. Hutton came to recognize that rocks were not original to the earth. They had not been born with the earth; they had not always been where they are seen today. Instead, they had formed by “secondary” processes and those processes are essentially the same ones we see operating today.

Most rocks that we see at the Earth’s surface are sedimentary. They mostly formed at the bottoms of oceans, according to the same processes that occur on sea floors today. If we study those sedimentary rocks, we find evidences of the ancient processes that formed them. They are stratified, that is they were deposited in horizontal horizons on horizontal sea floors. They are composed of sediments that match their environments of deposition. Sandstones are composed of shallow water sands; shales are composed of hardened deep water muds, and so on.

That influences how we geologists study sedimentary rocks; we examine them and search for modern ecologies where similar sediments accumulate today. Our Catskills are composed of sandstones and shales that formed in a great delta sequence. We find petrified rivers and petrified floodplains. We find lithified ponds, marshes and swamps. In short, we find thousands-of-feet-thick sedimentary rock sequence’s that identify the Catskills as a great petrified delta. We call it the Catskill Delta. The theory of rocks and the glacial theory guide the two of us to a greater understanding of the Catskills, something we share with you week after week.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

At last, a real floodplain!

The Catskill Geologists; The Mountain Eagle; Apr. 26, 2019

Robert and Johanna Titus

We have been writing about valley floors a lot recently. Those are the flat or nearly flat valley bottoms. Typically, people look at them and refer to them as “floodplains.” But we have been finding other explanations and other geologic histories for them. Those valley bottoms that have gentle downstream slopes are likely to be ice age features called outwashes. They are sediments left behind by melting and retreating glaciers. They are mostly mixtures of sand and gravel. We saw a good one near the village of Preston Hollow in a column a few weeks ago. Other valley flats were actually the bottoms of glacial lakes. Many of our Catskills valleys were flooded with water at the end of the Ice Age. Fine grained silts and clays accumulated in those lakes and, after they drained, flat valley floors were left behind. We saw a good example in the valley of Batavia Creek, west of Windham. That valley floor looks like a floodplain, but it isn’t: it’s a very old lake bottom.

Well, our readers are not shy; soon we received emails asking us where we they could go and see a genuine, authentic floodplain. So, that will be the topic of this column. But first let’s introduce you to what features serve to demonstrate a proper floodplain. And the best of those features is the river meander. A meander is just what the term implies. It is found where a river winds its way around a broad sinuous loop. Take a look at our first illustration (courtesy of Wikimedia commons).

This picture shows a stream channel rounding three meander bends. The heavy dark line shows the deepest, fastest flow of water, called the thalweg. The flow is thrown up against the outside bank where it erodes a steep slope, the cut bank. The sediments on the inside of the meander are called the point bar.

Now that you know some of the terminology of streams meanders, let’s go and look at some. We would like you to take Rte. 23 to Stamford and turn south onto Rte. 10. As you drive south, you will see the West Branch of the Delaware river to your left (east). At about a mile south of Stamford you should be able to see the view on our second illustration. It shouldn’t be too difficult to find a place to safely park and get out to take a good look. There, down below you, is a fine set of meanders. The river heads downstream, turns around and actually flows upstream and then turns around again. All the time it is crossing a floodplain. If you prefer, Google earth can do much of the traveling for you. It will give you an excellent view of these meanders from above.

Now, let’s get to the confusing part. There is no reason, given time, that a floodplain could not develop upon an old lake bottom. There are some fine meanders on lake deposits in the upper Batavia Kill. In fact, we have not been down to the valley flood on the West Branch of the Delaware, and we are not absolutely sure that there is no lake bottom down there. So, a lake bottom is a lake bottom until it becomes a floodplain.  And that is something that just takes time. But, as we always say, “this is geology, we always have lots of time.”

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Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist. Read their blogs at “thecatskillgeologist.com.”

Windham High Peak’s peak

The Catskill Geologists; Apr. 5, 2019

Robert and Johanna Titus

It won’t be long before the leaves are out, and it will be summer again. That will be just fine with us; it will let us out to go see all sorts of geology – sort of. In a way we wish we could make one big modification with winter. We wish we could make it a lot warmer. You see, for geologists, there are real advantages to having a season when there are no leaves. They typically get in the way of seeing the rocks. But it is so cold. So, if we had our way, it would be warm all year round, but there would still be pretty fall foliage and a “winter” without leaves. We would get out and do a lot of geology during that kind of winter. Oh well, we just have to deal with the seasons as they are.

Take a good look at our photo. It shows the summit of Windham High Peak as we see it right now in late February. Notice that you can really see the rocks up there. Look carefully. Those rocks are stratified; they are layered. They represent successive chapters in the geological history of the Catskills. These rocks are old, they date back about 385 million years, to what’s called the Devonian time period. Each horizon is petrified sediment. These layers were once sand, silt and clay, deposited on top of the Devonian Catskill Delta. It was big, even larger than today’s Mississippi Delta.

Exactly what kinds of rocks are they? You might think that they are too far away to tell, but that is not the case. The light-colored horizons were covered with snow when we took the photo. The dark strata somehow escaped the snow. That tells us a lot. Those dark horizons are cliffs; they are vertical, so no snow accumulated on them. The light-colored strata are not cliffs; they have relatively gentle slopes and did indeed pile up snow. So, the cliffs are dark, and the gentle slopes are snowy white. That’s nice but just what, exactly, does that tell us about rock type? A lot — it turns out.

The cliffs are composed of tough stuff, sandstone. Throughout the Catskills the thick sandstones are ancient river deposits; these were the sands that filled the river channels of the Devonian aged Catskill Delta. Gentle slopes are composed of softer rocks, these are mostly shales composed of silt and clay. Those are the old floodplain deposits. They are too soft to make cliffs; erosion always sculpts them into gently inclined slopes.

Please remember all this, next summer, when you are out climbing trails up the slopes of our mountains. You will commonly find yourself ascending relatively gentle slopes and then you will come across the trail blocked by a steep sandstone ledge. Suddenly you will have a little climbing to do. But, above that, you will find another gentle slope which will bring you to another sandstone. And so on, until you get to the very top of the trail — and of the mountain. You will have been climbing across Devonian stream channels, one after another. You will have been hiking across one Devonian floodplain after another. But, of greatest importance, you will be hiking with just a little more awareness of your surroundings; a little more real understanding of them. You, also, will have just a little bit more true comprehension of our mountains. And that is what this column is all about.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.